In this introductory textbook chapter, energy is defined and its sources, forms, and flow are introduced. Students are introduced to the first law of thermodynamics, conservation of energy. The resource includes links to current news articles, and a...(View More) suite of pre and post unit assessments. A teacher's guide supports classroom use. This is the first chapter in the unit, Energy Flow, exploring the flow of energy through the atmosphere, oceans, land, and living things over short and long timescales. The resource is part of Global System Science (GSS), an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.(View Less)